The extracellular matrix is an essential component of animal form and as such undergoes extensive modeling during growth and embryonic development. Many of the genes for structural components of the extracellular matrix, and for specific degradative enzymes and their inhibitors, have been identified and cloned. However, much less is known about how expression of these genes is regulated in time and space during embryogenesis and how this may be perturbed by teratogens or congenital abnormalities. The aim of this proposal is to establish an integrative approach to this complex problem by a) comparing in developing mouse embryos the temporal and spatial patterns of transcription of a number of different matrix associated genes using the techniques of Northern analysis and in situ hybridization. Detailed studies will be made of genes for the metalloproteinase, transin (stromelysin), and the metalloproteinase inhibitor, TIMP, compared with the Ca++-binding proteins Sparc (osteonectin) and 2ar (osteopontin), b) defining the DNA sequences in the mouse Sparc and rat transin genes which control their correct tissue and stage-specific expression during embryogenesis using transgenic mice, and c) studying the way in which the vitamin A derivative, retinoic acid, a low molecular weight morphogen and teratogen with profound effects on proliferation and cell differentiation, regulates extracellular matrix associated gene expression. The model system to be used is the induction of the Sparc gene in mouse F9 teratocarcinoma cells. These proposals will be carried out in the context of other studies on genes regulating embryonic development and the abnormal behavior of cancer cells within the environment of the extracellular matrix.